A mobile communications network is typically made up of a plurality of cells. Each cell includes a radio base station, with each base station connected to a mobile switching center or a packet service node that manages communications sessions between mobile stations and terminals connected to a public switched telephone network (PSTN) or a packet-based data network. Communications between mobile stations and base stations are performed over wireless links.
Traditional wireless protocols define circuit-switched communications. Such protocols include time-division multiple access (TDMA) protocols or code-division multiple access (CDMA) protocols. In a circuit-switched network, a channel portion between two endpoints (e.g., two mobile stations) is occupied for the duration of the connection between the endpoints.
However, with the wide availability of the Internet and intranets, packet-switched communications (e.g., web browsing, electronic mail, and so forth) have become common. Generally, a circuit-switched connection is an inefficient technique for communicating packet data. As a result, third generation (3G) and beyond wireless technologies are being developed to provide higher bandwidth and more efficient packet-switched communications (of data as well as voice and other forms of real-time data) over wireless networks.
One example of a packet-switched wireless technology is the CDMA 2000 family of standards, also referred to as the IS-2000 Standards, which is developed by the Third Generation Partnership Project 2 (3GPP2). A CDMA 2000 wireless communications system is capable of supporting both circuit-switched services and packet-switched services. On the TDMA side, packet-switched wireless communications protocols have also been developed, including the Enhanced General Packet Radio Service (EGPRS) protocol as defined by the 3GPP (Third Generation Partnership Project) UMTS (Universal Mobile Telecommunications System) Release 1999 Standard.
In packet-switched communications, packets that are sent across a data network are routed based on a source network address and a destination network address contained in each packet. In one example, packets sent over a packet-based data network are defined by the Internet Protocol (IP). IP defines IP network addresses that are used by network terminals and routers to communicate packets among each other.
Often, a terminal or router on a network is aware of a static symbol (e.g., an alphanumeric name such as user1@nortelnetworks.com) associated with a destination terminal. To map this static symbol to a numerical IP address, a domain name system (DNS) server on the network is accessed. The DNS server includes a database that maps static symbols of various nodes on a network to their respective IP addresses.
As with every other node on a data network, for a mobile station in a mobile communications network to communicate with another entity on a data network using an alphanumeric name or other static symbol of the other entity, the mobile station needs to perform a DNS lookup to determine the IP address of the other entity. To access a DNS server, the mobile station needs to be aware of the IP address of the DNS server. However, existing packet-switched wireless protocols do not define an efficient mechanism for communicating the network address of a DNS server to a mobile station.